1. Field of the Invention
The present invention relates to a resist coating and developing (hereinafter abbreviated as “coating/developing”) apparatus and method for coating a substrate with a resist film, and developing the resist film after exposure to form a resist pattern, and more particularly to a resist coating/developing apparatus and method which, by flattening the resist pattern, can reduce the line width roughness of the resist pattern.
2. Description of Related Art
In order to manufacture semiconductor integrated circuits with higher levels of integration, there is a demand for the production of finer circuit patterns. For example, the critical dimension of (CD) of an etching mask is reaching 32 nm or even 22 nm, which values are lower than the resolution limits of existing exposure apparatuses. In the formation of the channel of a field-effect transistor (FET), having such a width, a large line width roughness (LWR) of resist pattern will lead to variation in the threshold voltage of the FET, causing problems such as worsening of properties or abnormal operation of the resulting integrated circuit.
To address such problems, Japanese Patent Laid-Open Publication No. 2005-19969 (JP2005-019969A) describes a method for flattening surface irregularities of a resist film uniform by supplying a solvent gas to a resist film to dissolve the surface of the resist film.
When supplying a solvent gas to a resist film in a resist coating/developing apparatus, it is possible that the solvent gas may diffuse in the resist coating/developing apparatus and a resist film before development may be exposed to the solvent gas. In the case where the resist film is formed of a chemically-amplified resist, an acidic component in the resist film can be neutralized by an alkaline component contained in the solvent, which may inhibit development of the resist film and can even make patterning of the resist film impossible.
Some solvents have a strong pungent odor. If a gas of such a solvent leaks from a resist coating/developing apparatus into the surrounding space, the diffused gas will give an unpleasant feeling to an operator of the apparatus.